It is well established in magnetic induction that a changing magnetic flux density in the presence of an electrical conductor can be exploited to cause an electric current. Static magnets, such as bar magnets, do not induce such electrical currents, as such magnets do not have magnetic fields that are time-varying. A common implementation of induced current in time-varying magnetic fields is a transformer. In typical transformer design, an alternating (AC or time changing) electric current in one winding will induce a time changing magnetic field in the iron core. This in turn induces a different current in the output winding.